Enhancement of the power conversion efficiency for inverted polymer solar cells due to an embedded CuxO interlayer formed by using Cu(I) acetate and Cu(II) acetate

Abstract

Structural, optical, and photovoltaic properties of copper-oxide (CuxO) thin films formed by using a sol-gel method were investigated. X-ray diffraction patterns showed that the CuxO films prepared utilizing Cu(I) acetate or Cu(II) acetate and annealed under ambient atmosphere at various temperatures were polycrystalline with two phases, Cu2O and Cu64O. Transmittance spectra showed that the energy band gaps of the CuxO thin films formed by using Cu(II) acetate were smaller than those formed by using Cu(I) acetate. Current-voltage results showed that the power conversion efficiencies of the inverted polymer solar cells utilizing the CuxO interlayer formed by using Cu(II) acetate were better than those utilizing the CuxO interlayer formed by using Cu(I) acetate due to the multiple band gaps of the Cu(II) acetate.